SUMMARY The Clinical Characterization Core (CC Core) has been carefully designed to support the science proposed in the five individual Projects while also advancing the ACE Center?s integrative mission: utilizing interdisciplinary approaches to answer critical questions about underlying mechanisms and biological pathways implicated in the expression of ASD-related symptoms across developmental epochs spanning fetal and neonatal, infant and toddler, as well as school aged periods. The overarching purpose of the CC Core is to provide the recruitment and scheduling infrastructure across all five ACE Projects, as well as comprehensive clinical characterization for all participants. The CC core draws on a highly trained group of clinicians and support staff who have extensive knowledge and long-standing experience working with individuals with ASD and their families. Centralizing the recruitment, scheduling, and clinical characterization efforts across Projects will ensure cost effectiveness, while capitalizing on expert clinical and technical skills. The CC Core will perform, assist, train, and support the implementation of a comprehensive set of characterization procedures. Moreover, the CC Core will train both pre and post-doctoral fellows. Clinical staff will consult as well as assist Project personnel in evidenced based strategies to use while working with children with ASD in order to increase the success rate of participant completion during experimental procedures. The Core?s objectives include: (1) supporting the various projects in executing highly complex daily operational and organizational tasks including recruitment and scheduling; (2) promoting synergy across projects via facilitation of enrollment in all eligible studies; (3) providing well-characterized cohorts of participants to the various project areas at the highest possible level of expertise, validity, and reliability; (4) maintaining reliability and validity, as well as other standards of clinical care, education, and training; (5) making available behavioral, diagnostic, and psychometric expertise to all Core users; (6) making data readily available to other investigators and to comply with NDAR requests. Via advancing these objectives, we will ensure cost effectiveness and quality control is maximized.